1 00:00:04,000 --> 00:00:08,000 Where is the best place to search for life beyond the Solar System? 2 00:00:09,500 --> 00:00:13,600 Astronomers using telescopes at ESO’s observatories in Chile 3 00:00:14,000 --> 00:00:20,000 have discovered three planets around a dim dwarf star just 40 light-years from Earth. 4 00:00:20,781 --> 00:00:27,004 These worlds have sizes and temperatures similar to those of Venus and the Earth. 5 00:00:27,045 --> 00:00:34,100 They may be the best targets so far found in the hunt for life elsewhere in the Universe. 6 00:00:38,000 --> 00:00:40,717 This is the ESOcast! 7 00:00:41,000 --> 00:00:48,751 Cutting-edge science and life behind the scenes at ESO, the European Southern Observatory. 8 00:01:01,100 --> 00:01:04,783 New telescopes and more sophisticated instruments 9 00:01:05,000 --> 00:01:11,200 have allowed astronomers to discover and study large numbers of planets around other stars — 10 00:01:11,205 --> 00:01:13,885 known as exoplanets. 11 00:01:14,000 --> 00:01:19,100 Now scientists are searching for planets where we could detect life in the near future – 12 00:01:19,300 --> 00:01:22,127 if it exists. 13 00:01:22,500 --> 00:01:28,000 Astronomers hope to find the characteristic signatures in the atmospheres of these planets 14 00:01:28,002 --> 00:01:32,602 of molecules that could indicate the presence of life. 15 00:01:35,820 --> 00:01:38,453 But there are billions of stars in our galaxy, 16 00:01:38,455 --> 00:01:42,563 so how can they find the kind of planets they are looking for? 17 00:01:43,100 --> 00:01:50,124 A type of tiny dim red star called an ultracool dwarf is a good place to look. 18 00:01:50,250 --> 00:01:58,228 They are the only places where life could be detected on an Earth-sized exoplanet using our current technology. 19 00:01:58,240 --> 00:02:02,547 The light from much brighter stars — like the Sun for example — 20 00:02:02,550 --> 00:02:08,143 would swamp vital measurements of the atmospheres of any candidate planets. 21 00:02:10,300 --> 00:02:16,027 An international team of astronomers has used the Belgian TRAPPIST telescope 22 00:02:16,027 --> 00:02:21,715 to monitor the brightness of an ultracool dwarf star in the constellation of Aquarius, 23 00:02:21,715 --> 00:02:24,897 which has been named TRAPPIST-1. 24 00:02:25,752 --> 00:02:28,500 They found that it faded slightly at regular intervals, 25 00:02:29,026 --> 00:02:34,200 indicating that three planets were passing between the star and the Earth — 26 00:02:34,201 --> 00:02:36,874 events known as transits. 27 00:02:38,055 --> 00:02:44,960 The host star TRAPPIST-1 is much cooler and redder than the Sun and barely larger than Jupiter. 28 00:02:45,000 --> 00:02:50,358 Stars like this are very common in the Milky Way and they are very long-lived. 29 00:02:50,390 --> 00:02:56,604 This is the first time that planets have been found around one of them. 30 00:02:59,200 --> 00:03:04,962 Transits like these provide a surprising amount of information about the planet. 31 00:03:06,100 --> 00:03:11,719 The team were able to tell that the three planets are very similar in size to the Earth 32 00:03:11,719 --> 00:03:15,620 and that they orbit very close to their dim parent star. 33 00:03:16,061 --> 00:03:24,300 But the really exciting result is that all three planets might have habitable regions on their surfaces. 34 00:03:24,350 --> 00:03:32,976 This study has found the first Earth-like planets that are well suited for the detection of biological activity. 35 00:03:36,000 --> 00:03:39,700 The next step is to make more detailed observations, 36 00:03:39,800 --> 00:03:46,089 using the next generation of telescopes; such as ESO’s European Extremely Large Telescope 37 00:03:46,150 --> 00:03:51,700 and the James Webb Space Telescope, scheduled for launch in 2018. 38 00:03:51,750 --> 00:03:56,329 That will allow astronomers to study the atmospheres of planets like this, 39 00:03:56,330 --> 00:04:03,500 and to search for molecules related to biological activity, like ozone, methane or water. 40 00:04:05,200 --> 00:04:12,637 Ultracool dwarf stars are common — they account for around 15% of the stars near to the Sun. 41 00:04:13,700 --> 00:04:18,396 So this discovery opens up a new direction for planet-hunting, 42 00:04:18,396 --> 00:04:29,402 a direction that is taking us one step closer to the goal of finding evidence for some kind of life on distant worlds. 43 00:04:48,635 --> 00:04:51,000 Transcription by ESO; translation by —